ulTaskNotifyTake() for binary/counting notification in FreeRTOS - Mini Project: Build & Apply

Using ulTaskNotifyTake() for Binary and Counting Notifications in FreeRTOS

📖 Scenario: You are working on a FreeRTOS-based embedded system where tasks need to wait for events signaled by other tasks or interrupts. You will learn how to use ulTaskNotifyTake() to wait for binary and counting notifications.

🎯 Goal: Build a simple FreeRTOS program where a task waits for notifications using ulTaskNotifyTake(). You will set up a task, configure notification values, and handle both binary and counting notifications.

📋 What You'll Learn

Create a task handle variable called xTaskHandle

Create a variable called ulNotificationValue to store the notification count

Use ulTaskNotifyTake(pdTRUE, portMAX_DELAY) to wait for a notification and clear it

Print the notification count stored in ulNotificationValue

💡 Why This Matters

🌍 Real World

In embedded systems, tasks often need to wait for events like sensor signals or communication messages. Using ulTaskNotifyTake() helps tasks wait efficiently for these events without wasting CPU time.

💼 Career

Understanding task notifications is essential for embedded software developers working with FreeRTOS to build responsive and efficient real-time applications.

1

Create a task handle variable

Create a task handle variable called xTaskHandle and initialize it to NULL.

FreeRTOS

# Create a task handle variable called xTaskHandle and set it to NULL
# Your code here

Need a hint?

Use the type TaskHandle_t and set xTaskHandle to NULL.

2

Create a variable to store notification count

Create a variable called ulNotificationValue of type uint32_t to store the notification count.

FreeRTOS

TaskHandle_t xTaskHandle = NULL;
# Create a uint32_t variable called ulNotificationValue
# Your code here

Need a hint?

Use uint32_t type and initialize ulNotificationValue to 0.

3

Use ulTaskNotifyTake() to wait for notification

Use ulTaskNotifyTake(pdTRUE, portMAX_DELAY) to wait for a notification and clear it. Store the return value in ulNotificationValue.

FreeRTOS

TaskHandle_t xTaskHandle = NULL;
uint32_t ulNotificationValue = 0;
# Use ulTaskNotifyTake(pdTRUE, portMAX_DELAY) and store result in ulNotificationValue
# Your code here

Need a hint?

Call ulTaskNotifyTake() with pdTRUE to clear notification on exit and portMAX_DELAY to wait indefinitely.

4

Print the notification count

Print the value of ulNotificationValue using printf to show how many notifications were received.

FreeRTOS

TaskHandle_t xTaskHandle = NULL;
uint32_t ulNotificationValue = 0;
ulNotificationValue = ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
# Print ulNotificationValue
# Your code here

Need a hint?

Use printf("Notification count: %lu\n", ulNotificationValue); to print the count.